By clone specific polymerase chain reaction (pcr) small amounts of DNA can be detected. We discovered 50 tcr gamma and 7 tcr beta sequences from skin probes of 47 patients with mycosis fungoides. From 15 respectively 5 patients n-specific primers were designed. In order to examine if there is a relation between frequency of circulating clonal cells and clinical course, for 4 patients circulating clonal cells were quantified by real time pcr in LightCycler. In two patients we saw a reciproce proportion, in one patient with tumourstage disease rising numbers of circulating clonal cells were seen during worsening of clinical course. Detection of clonal rearrangments in skin and blood probes of patients with small plaque parapsoriasis could be a hint for classifying SPP as a lymphoma. In 6/14 patients we designed a clone-specific primer for circulating clonal rearangments. Despite performing a nested pcr circulating clonal rearrangments could not be detected in skin lesions of these patients.